Machine for the continuous casting of films directly from solution



Aug. 4, 1959 A M MARKS 2,897,544

MACHINE FOR Tf-IE OONTINUOUS CASTING OF FILMS DIRECTLY FROM SOLUTION Filed June 16. 1953 2 Sheets-Sheet 1 2 r-"l m -4 L' i if 1 c 5 I4 15 2O 1 L/ 16 I5 5 55 Z6 Q A I!" INVENTOR. HMUZM-MCLT'HAS ATTORNE Aug. 4, 1959 M. MARKS MACHINE FOR THE CONTINUOUS CASTING OF FILMS DIRECTLY FROM SOLUTION Filed June 16, 1955 2 Sheets-Sheet 2 IINVENTOR.

Elk/u: M. Max:465 WMM ATTORNEY MACHINE FOR TI-D3 CONTINUOUS CASTING F FILMS DIRECTLY FROM SOLUTION "Alvin M. Marks, Beechhurst, N .Y., assignor to Mortimer M. Marks, Beechhurst, N.Y.

Application June 16, 1953, Serial No. 362,043 8 Claims. (Cl. 18-15) This invention relates to a machine for forming continuous, uniform foils from solution, and more particu larly to the manufacture of a foil capable of plane polarizing light transmitted therethrough.

Previously known devices for continuously producing foils from solution have employed doctor blades, moving belts, troughs, drums, dipping, and the like. In each case, the article produced lacked the uniformity and optical qualities which are essential to the functions of the foils herein described. All of the prior art devices employ relatively complex coating structures having linear relative motion, which motion gave rise to periodical thickness variations or striae.

Accordingly, it is an object of the present invention to provide apparatus for applying a casting composition to a surface by using a flowing technique to produce a highly uniform coating thereon.

Another object of the present invention is to provide a device for producing foil, uniform and smooth throughout its structure.

A further object of the present invention is to provide means for producing extremely thin uniform foils having certain optical properties, continuously and directly from solution.

Another object of the present invention is to provide means for forming a light polarizing foil in a continuous operation from solution.

An object of the present invention is to provide a devide for the rapid, continuous production of a thin polar izing structure on a supporting transparent foil.

A further object of the present invention is to provide apparatus for providing a solution Which will pass directly into a substantially continuous polarizing crystal under certain conditions of operation, to be hereinafter described.

The invention consists of the construction, combination and arrangement of parts, as herein illustrated, described and claimed.

In the accompanying drawings, forming a part hereof, is illustrated one form of embodiment of the present invention, in which drawings similar reference characters designate corresponding parts, and in which:

Figure 1 is a somewhat diagrammatic vertical section, taken through a complete embodiment of a foil and light polarizing material-forming machine made in accordance with the present invention.

6 Figure 2 1s a view in front elevation, taken on line 0 2-2 in Figure 1, looking in the direction indicated by the arrows.

Figure 3 is a fragmentary view, somewhat enlarged, taken at the foil deposition station in the present invention.

Referring to Figures 1 and 2, it indicates a large disc which may be of the order of 6 to 12 feet in diameter, comprising a sheet of plate glass having a suitable thickness and a highly polished plane casting face thereon. For the purposes of the present invention it was necessary to provide a large, plane, chemically inert surface.

2,897,544 Fatented Aug. 4, 1959 The disc 10 is suitably mounted for rotation, as for example, by means of a central opening 11 therein, within which there is disposed a hub 12. The hub 12 is provided with a rear flange A and a front flange B. The disc 10 is suitably cushioned and clamped between rubber sheets C, by means of bolts D which are inserted through holes drilled in the disc 10. The hub 12 is keyed to a shaft 13, which shaft is journaled within bearings 14 and 15. The bearings 14, 15 are carried upon a suitable support 16, which may be secured to a frame, generally indicated at 17 in Figure 1. The shaft 13 is driven from a source of power (not shown) which is linked by means of some suitable drive member, such as a chain and sprocket 18, to a worm 19, which engages a worm gear 20. The worm gear 20 in turn is keyed to the shaft 13.

The source of power (not shown) is applied to the driving mechanism through a variable speed drive device, so as to produce a slow but uniform rotation of the casting disc 10. For example, one complete rotation of the disc every thirty minutes may be desirable under certain conditions and with certain casting compositions. The period of revolution, however, must be variable so as to adapt the device for the casting of a wide variety of materials under varying conditions of temperature, humidity, air flow, and the like.

The casting composition is brought to the disc 10 from a feed tank 21, best shown in Figure 2. The feed tank 21 is preferably located above the point of application, so as to permit a gravity flow of the casting composition through a feed line 22, and out of a nozzle 23, which is disposed so as to direct the solution at the casting disc 10. Alternately, suitable pumping means (not shown) may be used to force the casting composition through the line 22 and out of the nozzle 23. The nozzle 23 is provided with an adjustable orifice so as to render it capable of handling casting compositions having different viscosities, and to control the flow rate of the solutions.

As the casting composition leaves the orifice of the nozzle 23, which may be located at a point spaced from the bottom of the casting disc 10, as shown in Figures 1 and 2, it falls upon the said disc 10 and flows downwardly along the line indicated at 24 in Figure 2. Due to the angular velocity of the leading edge, the stream of the casting composition makes an angle with the vertical as it flows downwardly across the disc 10. The angle indicated at 0 in Figure 2 will depend upon the speed of the disc 10, the viscosity of the casting composition, and the flow rate of said composition.

It has been found desirable to minimize the flowing rate so that the leading edge 24 of the flowing composition inclines to a maximum angle, while at the same time covering the entire surface between the point of application of the composition and the edge of the disc 1i below the nozzle 23. If the rate of flow is too slow, or if the speed of the disc 10 is excessive, the line of flow 24 will be irregular, giving rise to unstable flow conditions and to an uneven coating of the casting surface.

As the disc 16) rotates there will thus be formed an outer band 25 which is completely coated by the composition. The composition deposited upon the disc 10 is maintained in its fluid state during its passage through the first quadrant of the disc by reason of a baflie 26 which is disposed in front of the casting disc 10, so as to cover the first quadrant. The baflie restricts overevaporation of solvent, and enables the solution to flow without solidifying.

The casting material spreads uniformly and smoothly upon the disc 10, as a result of the fluid condition of the composition throughout its travel around the first quadrant. The excess fluid drips off the edge of the casting disc into a trough 27 located beneath the disc 10, to receive the said excess casting composition. The fluid passes from the trough 27 into a lower tank 28, whence it may be reused after being passed through suitable filters (not shown) By allowing the coating to flowin the manner described above, an extremely uniform coating may be produced on the "face of the casting disc 10, which coating may have a thickness rangingfrom approximately 0001" to .0006" upwardly, as desired, depending upon the factors of viscosity, temperature, speed of deposition, and the like, aspreviously-indicated. -As thecoatedportion 25 of the disc 10 emerges from behind the battle 26 into the second quadrant 29 of the dise s travel, -the solvent within the coating composition begins to evaporate. The evaporation of 'the said solvent continues throughout the passage of thecoated band v25 through the third quadrant 30 of the discs travel. As the partially dried composition 25 reaches a point approaching the :end of the third quadrant 30, and while it is still in the form of a. viscous solid solution, it is pulled from the casting surface of the disc 10. The point at which the solid solutionleaves the disc 10 is hereinafter referred to as the take-off point, and is generally indicated at 31 in Figures 1 and 2.

By-reason of the-fact that the casting composition'fi'ows upon a rotatingcasting surface, the direction of flow is caused to change continually. As a result, the striae, which usually form in films fiowing intonly one direction, are greatly minimized. Such irregularities as may remain in the flowing-operation are almost completely eliminated at the film take-off point, hereinafter more fully set forth and-described.

The composition is flowed upon the casting surface near the bottom of 'the casting disc 16, and is pulled from the disc 10 at a point roughly 270 removed from the eastingstation, in a direction which is at right angles to the direction of the striae. As a result of this arrangement, the take-01f force tends to stretch the'film at approximately-right angles to its originalflow-ofidirection and thus eliminate said striae from the film, thereby:=producing film uniformity hitherto -unobt-ainable-by previously knownfilm casting devices.

While the castingdisc 10 :has been illustrated and deseribed-as being vertically disposed, it is within the ,purview of the present invention to employ other angles of inclination fort-he casting disc, it beingone of the purposes'of this invention 'to provide a fihn forming-structure which will cause a radial flow of casting solution directed thereon so as to form a uniform film upon the existing surf-ace,-and atthe same time dispose of surplus casting composition material.

The manner i-n which thesolid solutionfihn 25 is deposited upona supporting base 33 is hereinafter --more fully described. 4 -Referring again to Figure 2, there is shown an enclosure 34 which surrounds'the'casting disc 10 and the apparatus which governs the deposit-ionof the-casting composition upon the said disc. Aninput'air duct 35 isled into the enclosure3'4 andan-air exhausting duct 36 is provided at another point in the wall of said .enclosure. A flow of air, free from foreign particles,.and having --asuitable speed temperature and humidity, is led into the enclosurefl by-way of the ductSS. The :air is directed across the face'of-the disc 10, in the'second and third quadrants thereofitorthe purpose of aiding the evaporationof the solvents from the band 25 of the casting composi-tion. The solvent-laden air is thereafter drawn from-the enelosure34 through the duct 36.

- -At-a point spaccd from the end of the third quadrant and just above the take-0E pointsitLftherev may be provided suitablyspaced knives '37- and :38, :located "near the inner and-outer edges of thecasting band 25. The knives-37, 38r-are spring-loaded so as' to cut through the band 25 and control the width of the strip of film 32 that is pulled from the disc 10. The excess material which lies between the knives 37, 38 and the edges of the cast material 25, is picked up upon a wind-up roll shaft 39, best shown in Figure 1. In this manner all of the material which has been cast upon the disc 10 is removed therefrom before the said disc passes into the fourth quadrant 40, after which, additional casting .solution is deposited thereonfrom the nozzle .23. It will be seen thata continuous film 25 may thus be cast directly from solution.

Referring again to Figure 1, there is shown, in Somewhat diagrammatic form, apparatus capable of taking the film 25 cast uponthe'disc 10 and depositing it upon a support 33. At the same time it is possible, as hereinafter set forth, to render the film 25 capable of plane polarizing light.

In forming the filnr25 @intoa planeupolarizer, .thetbase tape 33 of the takc-otf iportion of the spresent apparatus, which .pulls the film 25 from the .casting disc 1'10, is driven at a speed substantially greater than theiravelnf the disc. Thus, for example, with the .casting composition described below, a :talreofl? speedtof-approximately five times that of thelinearmean-circumferential speed of the disc 10 has been employed. This differential in speeds provides a linear extension of the film 25 by .aiactor of approximately 5 to l, and to an extent sufiicient to align'and crystallize the molecular structure @of the film 25 at the point indicated at 41tin Figures 1 and 3, which is the place of deposition :of the film v.25upon the supporting structure 33.

The extension of'the film by a'factorof approximately 5 to 1 converts thefilmintoa crystal havingdhe inherent properties of polarizinglight. It will thus'beiseen that there have been provided means for directly Iconverting a solutionintoa light polarizer directly from said solution onto a support member.

Referringzagain to Figure 1, there are shown-a-series of rollersby means of which thefilm Zitaken'fromthe castingdisc It), may be handled throughout the various coating and drying operations necessary to finish-thesaid film. The aforementioned rollers are driven byacommonchain and. sprocket drive (not shown), thesprockets being attached to the roller shafts. The supporting film 33, which may 'be cellulose acetateor some other transparent, translucent, or suitable material, -is--maintained under tension by meansof a friction drum 42, whiehis connected to the feed roller 143. Inthis'marmer the supporting material 33 is caused to travel forward uniformly over all of the rollers, and carry thereon the film 25 throughout the various stages, hereinafter described-until it is finally Wound upon the roll indicated at 61 in "Figure .1.

After the supporting material 33 leaves the roller 43, it is coated on one surface with suitable coating material 45. The coating 4'5'is applied by-meansofa coating roll 46, which revolves within a feed tray 47, which tray is supplied with a continuous quantity of coating material from a reservoir 48 of suchmaterial by-way of a line 49, leading from the reservoir to the tray 47. The coating roller 46 revolves in a clock-wise direction in Figured, at a speed somewhatgreater than the linear speed'ofthe supporting material 33. As a result'of the diiferential'in speedof thesupp'orting material 33 and theroller 47, there is created a capillary, generally indicated at'Stl, which is defined by the closest proximity of the roll-47, tothe supply material .33. No actualcontact isnecessary between the roll 46 and the supporting material 33, the .small gap therebet'ween being bridged by the coating:material. in the form of the capillary .50.

. The coating material 45 is;.partial ly=dri ed in iitswforward travel :over the succeeding rolls 52-and 53. Thereafter, and While still -containing solvent an'd :capable'iof flow, the supporting material 3.3 Withits coating -ifilthereon, is brought into contact with the film 25 comprising the solid viscous solution taken from the casting disc 10.

The support member 33 is brought into contact with the cast film 25 coming from the glass disc 10, as the support member 33 reaches the roll 54. A fragmentary view somewhat enlarged, of the process at this stage is shown in Figure 3. As the supporting medium 33, and the cast film 25 reach the roll 54, they are both traveling downwardly, but with differing linear speeds, the linear speed of the supporting film 33 being considerably greater than that of the travel of the mean circumference 32 of the disc 10. Thus, for example, the speed of the supporting medium 33 may be faster than that of the film 25 by a factor of 5 to 1. As a result of the differential in speed, and the joining of the film 25 to the supporting medium at 41, the cast film is subjected to a linear stretch. The film 25 contains a considerable amount of solvent at this stage of the process, which allows the linear high polymeric molecules contained within the membrane to flow viscously into parallel relationship. Slip during the stretching stage compensates for the difierence in linear circumferential speeds on the inside and outside of the band 25 coated upon the disc 10. The resulting properties as to orientation, polarization, and thickness, are substantially constant across the width of the film 25. Evaporation of the solvent from the cast film continues as indicated by the arrows in Figure 3, throughout the stretching process, and after the said cast film 25 is secured to the supporting medium 33, as indicated below the roll 54.

At the region where the stretched cast membrane 25 comes into contact with the supporting medium 33, the coating material 45, which still contains a considerable amount of solvent, flows into the interstices at the place of joining, generally indicated as 41a in Figures 1 and 3. The air is thereby excluded from the joint between the film 25 and the supporting medium 33.

After the cast film 25 is stretched and deposited upon the supporting medium 33, as previously described, the assembly is passed around a roll 55, and thence upwardly into a heated enclosure 56, Within which the evaporation of excess solvent is substantially completed, and the linear molecules of the film 25, due to the elimination of said solvent are caused to lie in close parallel relationship. Thereupon, the forces of crystallization establish the molecules into a regular lattice. It is within the purview of the present invention to lead the film and supporting medium assembly from the heating chamber 56 over a roller 57, and into a second capillary coater 58, comprising a coating wheel 59, moving within a feed tray 60, which tray is fed by a constant supply of coating material (not shown). By this means a top coating of lacquer of some suitable composition, which may be for example, a nitrocellulose lacquer, may be applied over the crystallized and oriented film 25, for the purpose of protecting or stabilizing the said crystal. Following the coating operation, the dried film may be wound upon a take-up roll 61.

Where it is desired to produce from the cast film 25 a continuous crystalline light polarizing coating after deposition upon the supporting medium 33, it is necessary to provide a chemical composition by way of a casting solution, for this purpose. The casting solution must contain linear high polymeric molecules capable of crystallization upon extension, containing reactive side groupings, such as hydroxyl groups. The solution must also contain polarizing substances, capable of inter-crystallizing with the high polymeric molecules, such as iodine or known dyestuffs. It has also been found desirable to include cross-linking agents such as tetra ethyl ortho silicate, capable of reacting with a side grouping of the said polymeric molecular chain, and thus cross-linking them in whole or in part, in any direction normal to the direction of the stretch of the film 25.

The adhesive coating 45 may contain further quantities of cross-linking agents, to approximately saturate any other side chain reactive groups, encountered in the stretched film 25. The elevated temperature during the final heating stage within the chamber 56 tends to drive off excess solvent which may contain uncombined excess tetra ethyl ortho silicate. These solvents are caused to evaporate through the deposited stretched film 25 from the underlying supporting medium 33, and those components not reacting with the reactive side chain groups of the polymeric chain, or with the other components present, are driven off in the form of a vapor.

If iodine is the active polarizing agent in the film 25, this too may be present in excess, and the excess uncrystallized polarizing component may also be driven 01f within the heating chamber 56.

The casting solution contains a linear polymeric structure material such as polyvinyl alcohol, cellulose hydrate, gelatin, carbox-y methyl cellulose, cellulose acetate butyrate, or the like, to which is added a suitable acid such as acetic acid, proprionic acid or butyric acid. Suitable solvents such as ethyl alcohol, water, or esters are employed to aid in the solution of the linear polymers and dyestuffs employed in the composition.

In addition, a material capable of polarizing light, such as iodine or certain well known dyestuffs, may be employed in the casting composition. Those materials should be soluble, compatible, and capable of intercrys tallizing With, or forming a dye-complex with the high polymeric component employed. It has been found desirable to employ a cross-linking material in the casting composition so as to stabilize the polarizing film cast therefrom. Tetra ethyl ortho silicate, boric acid, glyoxal, and other cross-linking substances, known to the plastics art, may be employed for this purpose.

Example of polarizing solution The following comprises a suitable solution and method of preparing same for use in conjunction with the present machine:

Solution A.Mix 1,000 parts by *weight of polyvinyl alcohol powder into a slurry with 4,000 parts by weight of ethyl alcohol. While stirring, add 500 parts of glacial acetic acid and 4,500 parts of water to make a total of 10,000 parts. Heat while stirring to C. to form a clear solution.

Solution B.To 500 parts of ethyl alcohol, add parts of iodine resublimed; heat to 70 C. until dissolved, and filter.

Solution C.To 4,850 parts of Solution A, add, while stirring and while at 80 C., the following:

700 parts by weight of glycerin 1650 parts by weight of glacial acetic acid 50 parts by weight of water 50 parts by weight of tetra ethyl ortho silicate 2700 parts of solution B at 70 C.

Stir and filter under pressure, and thereafter allow to cool to room temperature.

The composition is then in condition to be used for casting directly upon the disc 10, from the nozzle 23.

-In the use of the above-described composition as gset forth herein, a reaction occurs in which the qlll gfc i ups of the polyvinyl alcohol react with the ethyl the cross-linking compound tetra ethyl ortho silicate to convert'the polyvinyl alcohol to a new material, herein termed alkane silicate.

This reaction has been described in connection with United States Patent No. 2,432,113, dated December 9, 1947, issued to Alvin Marks, Gerhart Weiss, and Alvin Robert Miller. The reaction proceeds to completion in the course of the casting, stretching and heating process. While the reaction is relatively slow, as long as an abundance of solvent is present, after the film 25 is formed on the disc 10, and evaporation begins, the reaction proceeds more rapidly and thereafter goes to completion throughout the various stages of the process.

. Example of 'base solution The coating'material 45, previously referred to inconnection with. Figures .1 and 3, preferably contains .a crosslinking solutionsuch as has been set forth above,;capable of reacting with thepolarizing film 25. A preferred coating materialor base solution 45, suitable for use, as previouslyset forth, is asfollows:

2330 parts by weight of -a 30% solution of %-S 9nd V nitro-cellulose inibuty'l acetate 4000parts'by Weight, of toluol 4000 parts by weight of ethyl acetate 1000 parts by weight of butyl acetate 300partsby weight of di-methyl-phthalate 10.0, parts by weight tetra ethyl orthosilicate {In the polarizing solution set forth byway ot example above, t-hcre-is utilized as a solvent plasticizenshort chain components having the same general structure as long ehain 'high polymeric molecules. For example, in the above formula, a high percentage of glycerin is employed. The glycerin acts as a solvent plasticizer. Theglycerin also has reactive hydroxyl groups, capableof reacting withthetetra ethyl ortho silicate, and the hydroxylgroup along the high polymeric car-hon chain. Thus, the east film 25, -which may. be initially highly viscous and capable of ready-flow and extensiommay become,.after the alignment of its :constituent long and short .chain molecules and their subsequent reaction with the cross-linking agent, fixed -.and substantially non-extensible -or retractable.

Whilethe foregoing description has been largely-devoted to the casting and forming f a light polarizing film, it is Within the purview of the present invention to cast other solutions in the aforedescribed manner, which solutions shall produce'films capable of performing other light filtering functions.

Thus, for example, the films so produced may have the optical properties of producing relative retardation -between the rectilinear components of polarized'light, as in thecaseof l. 4. or /2 wave plates. Such'foils-may also be only relatively slightly stretched and non-crystalline, and .containdyestufis: approximate to their action;asoptical filters, being thus made capable of absorbingaparticular range ofsthe spectrum, such as in the ultra-violet, visible/or infra-red spectrum.

In lieu of the flexible support member 33, described above, glass plates may be employed. The glass plates may be formedupon asu-itable carrier memberand the film 25 deposited directly on the surface thereof. In this manner a polarizing cry-stallinefilnrsurface may be deposited directly upon the glass plate.

It is also within the purview of-the presentinvention to employ the above -.'described device and process for the purpose of casting and producing continuous lengths of highly uniform film material, which material may have usesdn the "lamination of glass, or for various other purposes, where the highquality and uniformity, and low cost of the product produced by the. subjectdevice andprocess, are required.

Having 'thus fully described the invention, what is claimed as-new and'desired to be secured by -Letters'Patent of the United "States, is:

Tl. Apparatus for "the continuous casting of flexible films from solution comprising, a source of castin material in solution, a rotatably mounted casting member in'the' form.;of a'glass disc, a casting surface upon said casting member, a line .connected .at .one end to the solution source and'having its opposite. end disposed so as to directa stream of solution upon the casting surface, a. source of rotary power connected to the casting memher to coni nuspusly revolve the casting member past the dispensing end of the lime and rolls adjacent .the casting surface to remove'the film therefrom afterxthe solutionhas become sufficiently solidified.

2. Apparatus for the continuous casting of flexible films from solution comprising, a source of casting material in solution, a rotatablymounted casting member, a casting surface-upon sa'idcastingmember, in the form of a vertically disposed glass -disc,a line connected at one end tofhesolution source and having its opposite end disposed so .as to direct a stream of solution upon the casting surface, a source of rotary power connected to the casting member tocontinuously revolve the casting memberpast the dispensing end of the line and rolls adjacent the casting surface toremove the film therefrom after the solution has become sufiiciently solidified.

3. Apparatus for the continuous casting of flexible filmsirom solutioncomprising, a source of casting material in ,solution a rotatablymounted casting member in the form of a glass disc, a casting surface upon said casting member, .al ne connected at one .end to the solution source and having its .opposite end disposed so as to direct astream of "solution upon the casting surface,

. an adjustable nozzle upon-the dispeusiugend of the line,

asource of rotary power connected to the casting member to continuously .revolve the casting member past the dispensing end of the line and means adjacent the casting surface :to remove the film therefrom after the solution has become sufiic-iently solidified.

4. Apparatus for the continuous casting of flexible films from solution comprising, a source ofcasting material in solution, a rotatably mounted casting member in the formof a vertically disposed glass disc, a casting surface upon ,saidcasting member, a line connected at one end to the solution source and having its opposite end disposed .so ,as-to direct a stream of solution upon the casting surface, an adjustable nozzle upon the dispensing end-of the line, a first source of rotary power consisting of ,a motor connected to a variable speed drive connected to thecastingmember to continuously revolve athefiasting mcmberpast the dispensing end of the liue,-:a second;sour,ce ofpowerconsisting of a second motor, .a second yariable speed-drive connected thereto and .rollsconnected to thesecondsource of power adjacent the castingusurface ;to :remove theentire film therefrom after .thesolution has become sufficiently solidified.

5. Apparatus .for the continuous casting of flexible films from .solution.-.comprising,a source of casting ma- 'terialin solution, :a rotatably .mounted casting member in the term of -a:.vertically.disposed.disc, a casting surface upon saidcastingrnembena lineconnected at one end to the solutionsource'and having its opposite end disposed as to directa streamof solution uponthe casting surface-at a point spaced from the bottom edge of said casting surface, a'sourceof rotarypower connected to the i casting vmember-"to continuously revolve the casting member past the dispensing -.end ofthe line and rolls adjacent the casting surface to remove thefilm therefrom after the 1 solutionhas become sufiiciently solidified.

- -6. Apparatus for :the continuous casting of flexible tfilms from'solution comprising, a source of casting material in solution, a-rotatably mounted casting-member in the formof a disc, a casting surface upon said casting member, a line connected at one end to the solution source and having-its opposite end disposed so as to direct -a stream -of solution upon the casting surface, a source cit-rotary power connected to the casting member to-continuously revolveithe casting member past the dispensing'end ofthe line,-and continuously change the direction of flow of said'fluid during'the initial portion of the casting operation, and rolls adjacent the casting surface to remove the'entire, film therefrom .afterthe solution has become sutficientlyqsolidified.

7. Apparatus for the continuous .castiugof flexible films *r'rornsolution comprising, a source of casting material in solution, a rotatably mounted casting memberin the form of a disc, a casting surface upon said casting member, aline connected at one end ,to the solution source and 'having its opposite end disposed so as to 9 direct a stream of solution upon the casting surface, source of rotary power consisting of a motor connected to a variable speed drive connected to the casting memher to continuously revolve the casting member past the dispensing end of the line, and continuously change the direction of flow of said fluid during the initial portion of the casting operation and rolls, and rolls adjacent the casting surface to remove the entire film therefrom in a direction substantially normal to the initial direction of solution flow on the plane of the casting surface after the solution has become sufficiently solidified.

8. Apparatus for the continuous casting and deposition of a crystalline light polarizing film from solution upon a support comprising, a source of coating material in solution containing linear high polymeric molecules capable of crystallization upon extension and a polarizing substance capable of intercrystallizing therewith, a rotatably mounted casting member in the form of a disc, a casting Surface upon the casting member, a line connected at one end to the solution source and having its opposite end disposed so as to direct a stream of solution upon the casting surface, a first source of rotary power connected to the casting member to continuously revolve the casting member past the dispensing end of the line, and continuously change the direction of flow of said fluid during the initial portion of the casting operation, a second source of power, rolls adjacent the casting surface driven by the second power source at a speed greater than the linear speed of the casting member to remove the entire film therefrom in a direction substantially normal to the plane of the casting surface, and impart a linear film crystallizing stretch to said film, a source of film support material, guide rolls between the support material source and the casting surface adapted to lead the said support material upon the film removing rolls and coating means between the support material source and the film removing rolls to apply a bonding solution to that surface of the support material which is brought into contact with the stretched film as they meet upon the film removing rolls.

References Cited in the file of this patent UNITED STATES PATENTS 1,466,733 Sulzer et a1 Sept. 4, 1923 1,880,605 Van Derhoef Oct. 4, 1932 2,123,902 Land July 19, 1938 2,176,516 Wilmanns et a1. Oct. 17, 1939 2,200,001 Kenyon May 7, 1940 2,246,087 Bailey et a1 June 17, 1941 2,327,765 Carver Aug. 24, 1943 2,398,435 Marks Apr. 16, 1946 2,439,802 Francis Apr. 20, 1948 2,445,579 Hyman et a1 July 20, 1948 2,560,038 Trainer July 10, 1951 2,728,952 Borushko Jan. 3, 1956 

